1. Field of the Invention
The present invention relates to the field of display devices, and more particularly to a display panel and a display device.
2. The Related Arts
The liquid crystal display panel industry has been developed for decades. The vertical alignment (VA) display mode is a common display mode of thin-film transistor liquid crystal displays (TFT-LCDs) for large-scale televisions due to advantages including wide view angle, high contrast, and requiring no rubbing alignment. Contrast is assessed according to the ratio between the brightness levels of the brightest condition and the darkest condition. The contents of a displayed image is displayed through differences between pixels and the simplest one of differences is “brightness” and “darkness”, and the larges a difference between the two, the better that a person may perceive. The human eye pupils will constrict or dilate in response to environmental illumination in order to control the amount of light entering the eyes. Within a normal range of illumination, when the illumination of the surrounding environment get brighter, the human pupils constrict to reduce the amount of entering light, and oppositely, when the illumination of the surrounding environment gets less bright, the pupils dilate to allow a larger amount of light to enter. Thus, in a relative sense, the influence of contrast on the perception of human eyes is greater than that of brightness itself.
Taking the VA display mode as an example, the brightness of the liquid crystal display panel is determined by the electrical voltage applied to two ends of liquid crystal molecules. The greater the electrical voltage is, the brighter a pixel will be. The electrical voltage applied to the two ends of the liquid crystal is determined by a potential difference between electrodes provided on the array substrate side and the color filter substrate side. Due to terrain difference of the film structures on the two sides of the array substrate and the color filter substrate, it is common that individual areas may demonstrate stronger electric field even the electrical voltage applied is identical and this would cause corner light leakage in a dark state, severely deteriorating the contrast of a product.
Taking a color-filter-on-array (COA, which is an integration technique that makes a color filter layer directly on an array substrate) liquid crystal display panel as an example, it comprises a first substrate and a second substrate that are opposite to each other. The second substrate comprises a color filter layer and a thin-film transistor device layer. The first substrate is formed with a black matrix (BM) and a conductive layer laid on the black matrix. Due the black matrix pattern, the conductive layer on the first substrate would demonstrate an up-and-down irregular structure. The second substrate is provided with a color resist layer that is generally of a great thickness so that a conductive layer (such as a pixel electrode) on the second substrate would be relatively flat. Upon application of an electric voltage to the conductive layer of the first substrate and the conductive layer of the second substrate, due to the difference of distance, the electric field may show different intensities in different areas, such that the intensity of the electric field is higher for areas where the distances between the two opposite conductive layers are shorter (such as the areas on the first substrate where the black matrix is provided) and the intensity of the electric field is lower for areas where the distances are longer. As shown in FIG. 1, since in the area where the electric field is stronger, the rotation of the liquid crystal molecules is greater, in a dark state of the liquid crystal display panel, an edge area (such as corners 102 of a light transmitting area 103) that corresponds to the black matrix 101 often suffers abnormality of electric field due to terrain variation and this leads to brightening and occurrences of light leakage.